[Speaker 2]
Hiroyuki Ishikawa, M1, SOKENDAI (Supervisor; Takayuki Kotani)
[Title]
Metallicity determination of M dwarfs through synthetic spectral fitting in the near-infrared
[Abstract]
Recently many exoplanet surveys targeting M dwarfs have been planned or conducted around the world. In order to discuss the parameters and population of the planets they will find, our understanding of their host stars are important. The precise parallaxes of the stars measured by Gaia or Hipparcos can be used to derive luminosities and then infer masses and radii, but not metallicities. The most common method to determine the metallicities of FGK-type stars is the synthetic spectral fitting in the optical region. However, M dwarfs have cool atmosphere which enable the formation of molecules with complex absorption bands, and so it is difficult to apply the method. Therefore, most of the studies about the metallicities of M dwarfs have been based on empirical methods so far. Thesedays, some high-resolution near-infrared spectroscopes are constructed and the synthetic spectral fitting begins to become possible in the near-infrared. It is promising method because M dwarfs is brighter and have fewer molecular lines in the near-infrared region than optical. In this presentation I introduce the paper by Onehag et al. (2012) who challenged it for the first time using CRIRES at ESO-VLT. We are planning to apply such method to later type M dwarfs by use of the data of IRD planet survey at Subaru.